Effects of Optimized Operating Parameters on Combustion Characteristics and NO_x Emissions of a Burner based on Orthogonal Analysis

To optimize the structure of the burner,improve the combustion performance,and reduce the emission of NO_x,a self-circulating low NO_x combustion technology was used to design a new type of flue gas self-circulating low NO_x burner.Based on previous research on the numerical model of combustion and the composition of mixed gas on combustion and NO_x emissions,the effect of various factors on the ejection coefficient of the flue gas self-circulating structure was analyzed using the orthogonal test method,and the burner operating parameters,such as preheating temperature and excess air coefficient,were deeply studied through the three-dimensional finite element numerical model in this paper.The results show that the diameter ratio of the nozzle and the length of the cylindrical section of the flue gas self-circulating structure have great influence on its ejection and mixing ability.The optimal ejection coefficient was 0.4829.Overall,the amount of NO_x emissions greatly increased from 6.23×10~(-6) (volume fraction) at the preheating temperature 973 K to 3.5×10~(-3) at preheating temperature 1573 K.When the excess air coefficient decreased from 1.2 to 1,the maximum combustion temperature decreased from 2036.3 K to 1954.22 K,and the NO_x emissions decreased from 352.29×10~(-6) to 159.73×10~(-6).     

汽车覆盖件修边与翻边工序的快速仿真系统

基于UGNX平台开发了覆盖件修边与翻边工序快速仿真系统(TFA).该系统基于有限元逆算法,根据翻边形状反向快速计算修边线尺寸以及翻边成形中可能出现的起皱和破裂等缺陷.由于修边线展开与翻边分析无缝集成UGNX中,避免了CAD与CAE系统数据转换时模型数据丢失和精度损失,缩短了工艺设计周期,为工艺设计人员提供一种方便的修边和翻边快速仿真工具.以汽车后围修边线展开与翻边成形为例,通过TFA计算结果与实验结果的比较,验证了TFA系统算法的可行性与精确性.     

重力式挡墙下基础的设计方法探讨

对于重力式挡墙下筏式条基,采用不同的布置方式直接影响其造价.文章从理论上探讨了筏式条基的合理布置,并且通过工程实例验证了当筏式条基截面中心偏离挡墙合力点为e0与B/30中较小者时,筏式条基按受弯计算所需的配筋要比筏式条基截面中心与挡墙合力点重合时节省9～14%的配筋.当筏式条基底部土层沉降已基本完成且能提供100KPa左右以上地基承载力特征值时,建议设计时采用方案2所述的挡墙基础布置方式.     

A 20.8-Gbps Dual-Carrier Wireless Communication Link in 220-GHz Band

With the successful demonstration of terahertz (THz) high-speed wireless data transmission,the THz frequencies are now becoming a worth candidate for post-5G wi...     

Certain classes of meromorphic multivalent functions

In this paper, we introduce and investigate two new classes of meromorphic multivalent functions. Such results as subordination properties, coefficient inequalities, convolution properties and integral representations are proved. Several sufficient conditions for meromorphic multivalent starlikeness and convexity are also derived.     

20%～70%阻抗区间内变压器结构方案的合理选择

介绍了阻抗调整的思路,给出了20%～70%阻抗区间内变压器的结构方案建议。     

采用磁力平衡方法的在线动平衡机技术研究(Ⅰ):基本原理和结构

提出了一种采用无接触同步旋转电磁力作为平衡矢量的在线动平衡机的设想。设计了相应的定子绕组结构。分析和计算了定子绕组方波供电时电磁力幅值与相位的波动误差,计算结果证明了方案的可行性。     

高海拔地区500kV变电站设备相间操作冲击放电特性

相间操作冲击放电特性是决定变电站设计尺寸的一个重要方面。为获得我国高海拔地区500kV变电站的设计依据,结合云南电网公司500kV建塘输变电工程,分别在3个不同海拔高度地区武汉(23m)、西宁(2 254m)、大武(3 742m),开展了模拟真型500kV变电站典型电极—软母线和均压环的相间操作冲击试验研究。利用升降法获得5～8m间隙距离内的相间操作冲击放电特性曲线,分析电压分配系数对相间间隙空气绝缘的影响,并按不同的海拔校正方法对试验结果进行校正分析和比较。试验表明:受海拔高度的影响,高海拔变电站设备相间操作冲击平均击穿场强较低海拔有明显的下降,相间操作冲击放电电压U50随着电压分配系数增大而增大。通过对比国内外不同海拔校正方法,建议高海拔地区500kV变电站均压环相间操作冲击海拔校正采用IEC 60071-2—1996标准的方法进行海拔校正;软母线相间操作冲击海拔校正采用带m因子的修正方法进行海拔校正。     

交流异步电动机轻载降压节能分析

基于近几年来全国范围内大量缺电，造成煤炭资源紧缺的现状，讨论了电动机降压节能原理及降压以后对电动机性能产生的影响，探讨了现有节能方法中的利与弊，并从理论上分析了降压节能的最佳系数。通过分析认证了降压节能具有合理性，具有很实用的价值。     

Dual-wavelength cascaded Raman fibre laser

Dual-wavelength lasing at 1480 and 1500 nm has been demonstrated from a cascaded Raman fibre laser with a WDM coupler and two pairs of Bragg gratings. Intensity-adjustable, wavelength-tunable laser operation was achieved by tensile stress wavelength tuning of the gratings